Abstract: A simple orthogonal plane coordinate system that is applicable to analyze the stability of soil slopes is set up. The numerical integral method of the stability analysis of slopes is presented based on the general limit equilibrium method. The integral formulae of the safe factors of moment equilibrium and force equilibrium for circular surface and compound surface are deduced. A simple and useful function of internal forces is proposed. The calculation and figure treatment are programmed according to the integral method of the general limit equilibrium. An example is given and compared with other methods.The distribution laws of sliding force, resistance, internal lateral thrust and shearing forces in the slope are shown by the figure treatment results. It is concluded that there is a critical equilibrium point in stable slopes.